Traverse shear mode piezoelectric chemical sensor

Abstract

The present invention relates to a process for sensing biological or chemical changes in molecular structural shape or mass of molecules attached to the surface of a transverse shear piezoelectric oscillating molecular sensing device driven by a network analyzer. The process comprises the steps of i) exciting the sensor device at a series of predetermined frequencies, ii) collecting data to determine values for the predetermined parameters of series resonance frequency shift (fS), motional resistance (RM), motional inductance (LM), motional capacitance (CM), electrostatic capacitance (Co) and boundary layer slip parameter (α); and iii) determining relative changes in the measured parameters to detect thereby any changes in molecular structural shape or mass at sensing device surface.

1. A process for sensing a chemical change in molecular conformation or mass of a biomolecule attached to the surface of a transverse shear piezoelectric sensing device driven by a network analyser, said change being attributable to a binding interaction between said biomolecule attached to the surface and a biological entity in a surrounding liquid medium upon exposure of the surface to the surrounding liquid medium, said process comprising the steps of:
 i) exciting said sensing device at a series of predetermined frequencies prior to and during exposure to the surrounding liquid medium; 
 ii) collecting data from the sensing device to determine values for parameters: series resonance frequency shift (fS), motional resistance (Rm), motional inductance (Lm), motional capacitance (Cm), electrostatic capacitance (Co), and boundary layer slip parameter (α); 
 iii) determining a relative change in said parameters in step ii) upon exposure of the surface to the surrounding liquid medium; and 
 iv) correlating the relative change in said parameters determined in step iii) with a calibrated set of data for said parameters to determine a change in molecular conformation or mass of the biomolecule attached to the surface attributable to a binding interaction upon exposure to the surrounding liquid medium; 
 wherein a change in boundary layer slip parameter (α) and an essentially zero change in the series resonance frequency shift (fS) confirms a change in molecular conformation and essentially zero change in mass of the biomolecule attached to the surface. 
 
     
     
       2. The process according to  claim 1  wherein said biomolecule attached to the surface is selected from the group consisting of proteins and nucleic acids. 
     
     
       3. The process according to  claim 2  wherein said proteins are selected from the group consisting of antibodies, enzymes, molecular receptors, receptor ligands and polypeptides. 
     
     
       4. The process according to  claim 2  wherein said nucleic acids are selected from the group consisting of DNA, RNA and oligonucleotides. 
     
     
       5. The process according to  claim 1  wherein said biological entity in said surrounding liquid medium is selected from the group consisting of proteins and nucleic acids. 
     
     
       6. The process according to  claim 5  wherein said proteins are selected from the group consisting of antibodies, enzymes, molecular receptors, receptor ligands and polypeptides. 
     
     
       7. The process according to  claim 5  wherein said nucleic acids are selected from the group consisting of DNA, RNA and oligonucleotides.